Biology (11th Edition)

Chapter 9 - Cell Communication - Review Questions - Apply: 2

Answer

C.

Work Step by Step

The appearance of a puff of calcium in the normally calcium-poor cytoplasm is quite noticeable to cellular machinery and can, thus, act as a signal (C.) B. is the opposite of this, and thus wrong, and A. can be eliminated since calcium ions are not synthesized (they are just a chemical element minus two electrons), and D. is wrong since calcium ions are stored in the endoplasmic reticulum.